gpu overclocking guide for beginners; prt2

Karl Is WrightHacks n Mods

Continued from prt1;

I assume absolutely no responsibility whatsoever, for any damage done to your computer, whether by following this gpu overclocking guide or otherwise.

Moding the VBIOS

VBIOS stands for Video Basic Input/Output System, think of it as being a small set of instructions, saved, not on your HD, not in your OS, but actually written onto the GPU itself. The instructions that tell your computer how much voltage to give the GPU, when to throttle it; a ruleset to revert to lower clockspeeds when a certain temp is reached (if your games often vary between smooth and laggy, this could be the cause).

That’s why you have to be very careful what you write on the VBIOS, because if you mess up and write settings the card can’t function with (voltage too low / high, clock speeds too high, causing lock-up…etc.) there’s no way to get to your operating system to re-write the values again. Even if you re-installed windows, it wouldn’t matter, the instructions aren’t written in windows, they’re written on the card itself. Putting it in a different computer won’t help, installing a different OS won’t help, if you trash your VBIOS your GPU is dead, unless you have some expensive BIOS writing equipment, or if you don’t mind ordering a new Ball Grid Array (BGA) and re-balling it with a soldering iron.

But relax, the good news is, so long as you just write the values you’ve already set earlier, you’ll be fine. If you increased your clock/mem speed and you were able to play Crysis 2 on max settings no-problem, then you should be fine to write those same settings to the VBIOS.

Why such a dangerous route?:

There are some advantages to moding the VBIOS of a GPU. One benefit is that the GPU will now run on the overclocked settings by default; meaning that it will report those settings as it’s natural settings to whatever OS it’s running under. So, if you wanted to switch operating systems, or re-install your current OS, and didn’t want to go through the hassle of re-installing overclocking software to tell the OS what settings to use, this will save you some time.

Or perhaps your preparing to put your older GPU up for sale, and you want to squeeze a bit more value on the price by being able to tell potential techno-phobic buyers that you’ve already overclocked the card for them.

Let’s get started.

The Clocks.

Open up NiBiTor.

File -> Open the VBIOS you saved earlier for the purpose of moding it.

The first thing you will see are a bunch of clock rates. Something like this;

click for full size

Since we’re over-clocking as opposed to under-clocking, we won’t worry about the bottom 3 profiles. Basically if you’re GPU was getting too hot, just on standard settings, then if you wanted to, you could just lower the rates for the bottom three or even all four profiles. But again, whether your raising or lowering your clocks, remember to test the settings out in your overclocker first! Makes sure your GPU can actually run at the settings your about to input. If you aren’t sure your overclocker has applied the settings, fire-up GPU-Z and check!

Now, for those of you who’re planing to increase your performance, place your tested clock settings into the Extra profile. Now you’re done… if you want to be done.


The Boot Settings.

File this more under the, bells and whistles, category if you like. Under boot settings if you’d like to make a rather benign change, you can edit the sign-on message displayed at boot. In my case I justed added the word, Overclocked, under what was already there.

click for full size


Seriously don’t mess with this unless you’re really brave, Or do a Google search for your GPU and see what someone else with the exact same model has been able to set it too (hint; Overclockers Forums is your friend).

If you do want to change the voltage, there are a couple of advantages.

One such advantage is that if you lower the voltage you may be able to keep your GPU cooler. Less voltage = less heat. Be aware that if you lower your voltage, you’ll need to lower your clock speeds. When experimenting with low voltage have your GPU on the lowest clock settings you can have it run on. Just be careful, lower the voltage too much and your GPU might not even be able to boot up. In which case, GPU = garbage.

Another advantage is that if you raise the voltage, you may be able to raise your clock speeds even higher that you could before. But be warned, more voltage = more heat. Also, you don’t want to kill your card by raising the voltage too high.

Click over to the Voltages tab to see what your cards voltages are set to. There will be a voltage setting for each profile. You should be okay to set each profile to a different voltage, or even to use the same voltage for all four profiles (though I don’t know why you’d do that), should you choose to.

To change the voltage,

Tools -> Voltage Table Editor

click for full sizeTechnically here, you can decide how many voltage entries you want, based on how many different voltage settings you plan on using. Normally two entries is about all you’d need, one for intense 3D gaming, and another for normal use (web, word processing…etc).

Hopefully you did some research to figure out what other people have set the same model GPU to and gotten away with. So you know how high or low you can go.

If you do, just input the desired voltages into however many of the slots you need.

In my case, my GPU came with an Extra Profile that was running at 1.05V and it was getting so hot, I could hardly even play chess on my laptop. While the other profiles were using 0.89V, so I just set my Extra Profile to run on 0.89V and underclocked it from stock clock speeds.

click for full sizeBecause the Extra profile only comes into the play when you’re doing your 3D gaming, I used it as a testing ground to see what voltages my GPU could run at, in this case, I’d incrementally lower the voltes for the Extra profile while keeping the other profiles at .89V and then I’d flash and restart. Upon restarting I’d open up GPU-Z and look at the sensors to monitor the V, then I’d open up furmark and run a benchmark, this would trigger the Extra profile and if my computer didn’t crash, it could handle the V. I only put experimental V settings in the Extra profile, because that way, even if it didn’t work, I’d still be able to boot into windows and, if need be, reflash the VBIOS with a higher voltage.

I also discovered that while the card was set to run on 1.05V, I could power it quite comfortable at near-stock speeds by running it at just .89V. Thus greatly solving my over-heating problem.

Since most of you are probably looking to raise your clock speeds, then you can just follow my lead, but raise the V instead of lowering it. Just raise the V for the Extra profile while keeping the other profiles at safe stock V settings. Then you can flash, boot, and benchmark with GPU-Z in the background. Don’t go changing clock speeds and voltage at the same time, just do one at a time, first wait until you arrive at a voltage you know you can work with.


Flashing the VBIOS.

Once you have everything setup, it’s time to flash the VBIOS. Flashing your VBIOS is the easiest and scariest part of this tutorial.

Open up a Command Prompt as an administrator.

You can do this by just opening up start, and typing ‘cmd’ into the search, when you see ‘cmd.exe’, right-click and run as admin.

Navigate the command prompt to the directory of your nvflash.exe and your rom to flash (they must be in the same directory).


nvflash --list

If you’d like to make yet another backup of your original VBIOS you may do so using the command;

nvflash -b backup.rom

You’ll see your GPU listed with a position given in <> on the left. If that position is 0, then don’t worry about it. However, if you have two GPU’s in SLI mode, then you’ll need to flash them with an added command.

If you DO have two GPU’s in SLI mode, use the following two commands (be sure to replace ‘name.rom’ with the name of the rom you want to flash):

nvflash -i1 -4 -5 -6 name.rom
nvflash -i2 -4 -5 -6 name.rom

Type the first command and hit Enter, wait for it to finish, then type in the second command.

If you DO NOT have two GPU’s in SLI, then it’s even simpler, just one command (be sure to replace ‘name.rom’ with the name of the rom you want to flash):

nvflash -4 -5 -6 name.rom

click for full sizenvflash May ask you if you’re sure you want to write this VBIOS and say something about an ID-Mismatch. Don’t worry about the ID-Mistmatch if it says you have one, basically that just means the VBIOS your flashing is different from the one on the card. You already know this and so you can just press, ‘y’ to confirm.

Now just wait for it to finish.


After you re-write the VBIOS, be advised that the changes made will not take effect until you reboot your PC.

So now you have to reboot your PC.

Once your PC has powered on with the new VBIOS and you get to your login screen, you can breath a sigh of relief.


That’s it for my gpu overclocking guide! If you enjoyed it, be sure to let me know in the comments, and share this post with your friends.